Ultimately, the crucial role of DUOX1 in human thyroid function was demonstrated in patients with congenital hypothyroidism (CH): two heterozygous missense mutations in DUOX1 and DUOXA1 in two patients can cause CH through disrupting the coordination of DUOX1 and DUOXA1 in the generation of H2O2. Here, DUOX1 is linked to congenital hypothyroidism.